Planets in binaries

1. Planets in binaries Sergei popov

2. Catalogue of planets in binaries http://www.univie.ac.at/adg/schwarz/multiple.html

3. S-type and P-type. And T-type! The central stars strongly perturb the region around them, clearing out orbits to distances of 2–5 times the binary separation. In addition to knownS-type and P-typeplanetary orbits, alsoso-call T-type planets,similar to Troyans,can exist.

4. Orbit stability S-type P-type Both estimates are given for e=0.

5. 1406.1357

6. S-type Distance ratio: Rplanet-A/RAB Mass ratio: MB/MA Musielak et al. (2005)

7. P-type Musielak et al. (2008)

8. Planets in triple-star systems Stable orbits of S-, P-, and T-typesare possible in different kinds of multiple systems. 1608.00764

9. Quadruple star systems 1608.00764

10. Statistics 1608.00764

11. First circumbinary planet found by microlensing Only triple lensing model (star+2 planets or planet+ 2stars)can fit the light curve. Subsequent HST observations favour the circumbinary model. Planetary orbit ~3.2AUOrbital period ~7 years Planetary orbit 1609.06720

12. Comparison Kepler planets have tight orbits, as if theymoved close to their starsafter formation.They are close to thestability limit. ac is measured in binary semi-major axis Circles show binary separation,And crosses – planetary.Vertical ticks mark the stability limit. 1609.06720

13. Search for binary component around planets hosts • Three techniques: • RV • AO • DA 1407.3344

14. Statistics of planets in close binaries 1407.3344

15. ETV: Eclipse timing variations http://astronomy.science.upjs.sk/projectdwarf/scientific-background/ CoRoT: 4 sec – for bright stars (12), and 16 sec – for dim stars (15.2 mag).Kepler: 0.5 sec – for bright stars (9 mag), and 4 sec – for dim stars (14.5 mag). HW Vir 1608.00764

16. Modeling ETV. S-type systems abin=1AUi=0 (planar orbit) Earth-like planets are undetectable Jupiters are 100% detectable 1608.00764

17. Modeling ETV. P-type systems abin=1 AU; ebin=0 1608.00764

18. Protoplanetary discs in binaries. S-type Discs in binaries might be truncated (at 1/3 - 1/4 of the orbital separation). Disc frequency for wide binaries issimilar to that in single stars,but for close binaries it is lower. Dust mass is smaller for smaller binary separation. Truncated discs with lower dust mass can bea bad place to form planets, especially massive. Discs in close binaries are also short lived.Also bad for planet formation, especially for giants. In 2/3 of close binaries discs live for <1 Myr. Temperature is higher in such discs,so dust growth can be less efficient. Perturbations in the disc also modifies planet growth. 1406.1357

19. Alpha Centauri-like binary In a compact binary systemplanet formation is possibleonly at small distances from the host star. 1406.1357

20. Water delivery Earth-like planets can be formedin a habitable zone in a compact binary. 1406.1357

21. Earth-like Snap shots of formation ofEarth-like planets in a HZ.In this study it was assumedthat the initial phases ofplanet formation have beensuccessful. 1406.1357

22. Accretion Accretion onto forming planetsin a binary system is influenceddynamically by the companion.High velocity collisionsresults in erosion, not in growth. 1406.1357

23. Other ideas for S-type • Several other ideas are discussed • Planet migration • Changing of the binary separation • Gravitational instability • Planets could be formed at different orbits, and then migrate outwards.Seems problematic to increase the planetary orbit significantly. • It is possible that some compact binaries have been wider, but thentheir orbits shrink due to interaction with stars in a cluster. • Gravitational instability in a protoplanetary disc can help to formplanets at larger distances avoiding problems with dust growth, accretion, etc. 1406.1357

24. Stability of orbits For slow (adiabatic)mass loss the orbitexpands as: If we considerthe planetary massas a very small value: 1204.2014

25. Star-hoppers In a binary if the primary is loosing massplanets can change the host.This is important to form some peculiar types of planets. M1=2 -> 0.55 Msolar M2=1 Msolar aini=90 AU 1204.2014

26. 1204.2014

27. Circumbinary (P-type) planets Inside the critical radiusorbits of light satellitesare unstable. A binary cleans out orbits around it up to 2-5 binary separations. Outside critical distance (except some resonances) there is a family of nested quasi circular (most circular) orbits, which behave quite similar to orbits aroundsingle stars.Beyond 6:1 resonance orbits are stable for small binary eccentricity.This allows to form planets around binary stars (in the circumbinary regime)in a usual way. 1503.03876

28. Most circular orbits Particles having these orbits make minimal radial excursions and never collide. 1503.03876

29. Planetary formation in P-type binaries Gas and small particles quickly settle to most circular orbits. In most circular orbits particles have low relative velocity.So, collisions are not destructive. And a set of lunar-size objects for planets as around single stars. • Still, there are problems with some known planets, as they are situated close to their hosts.It requires too massive discs (>10 times more massive than in the classical MMSN scenario).Four scenarios are discussed: • In situ formation • Migration – then assemble • Migration through a gas disk • Planet scattering Analysis of six known planets favours“migration –then assemble” or “disc migration”,and in few cases – scattering, but not in situ formation. 1503.03876

30. In situ formation in massive discs Minimal surface density necessary to buildknown planets.Lower curve – MMSN (Hayashi 1981)Upper – multiplied. Typical disc masses in the MMSN 0.01 Msolar. It is difficult to explain massive planets by in situ formation. Light planets can form at small distanceswithout migration. 1503.03876

31. Another circumbinarydisc model Angular momentum in injected to the disc from the binary Accretion to the binary from the disc can be smallor even zero. 1509.07524

32. Energy in the disc • Disc has three sources of energy: • Viscosity; • Illumination; • Dissipation of shock generated by the binary. 1509.07524

33. Important issues for planet formation • Disc is more massive than around a single star • Relative speeds at collisions are smaller • Isolation masses are larger • Ice line is shifted outwards • Dissipation of the binary-driven density waves dominatesheating of the inner disk, within 1–2AU Circumbinary disks are in many ways more favorable sites of planet formation than their analogs around single stars 1509.07524

34. Binary evolution due to the disc The binary can coalesce due to tidalinteraction with the disc. 1509.07524

35. Habitable zone calculations 1406.1357

36. Calculations 1406.1357

37. Weight coefficients 1406.1357

38. Examples Dark green – narrow HZ.Light green- empirical HZ. 1406.1357

39. Examples: eccentricity=0.3 M-dwarf is the primary 1406.1357

40. Examples: eccentricity=0.3 F-star is the primary 1406.1357

41. Habitable zone calculation. II. Circumbinary Let us start with single stars Here luminosity and flux are in solar units, anddistance – in AU. 1211.2812

42. Binary stars G2V+K5V0.1 AU 1211.2812

43. Stellar flux map G2V+K5V0.1 AU 1211.2812

44. HZ edges Inner edgeOuter edge Inner edge M0V+M0V0.5 AU G2V+K5V0.1 AU 1211.2812

45. Stability of the planetary orbit 1211.2812

46. On-line calculator Described in 1401.0601T, L, and M can be changed independently(i.e., there is not fit for the MS, etc.) http://astro.twam.info/hz/

47. Multiple systems The method allows to make plotsfor any number of stars.However, consistency of allconditions (orbital stability, etc.)is not automatically controlled. http://astro.twam.info/hz/

48. KIC 4150611 http://astro.twam.info/hz/

49. KID 5653126 http://astro.twam.info/hz/

50. http://astro.twam.info/hz/